4 - 4.1 Avian Skeletal and muscular system

• newEditor

Unit 314:
Avian Health and Husbandry

Topic 4.1 – Avian Anatomy and physiology

Skeletal and muscular system

How much of the mammalian skeleton do you remember…

Write down what you can remember

2 minutes

Can you name the 24 bones?

Musculoskeletal system – mammalian skeleton

1. Cranium

2. Atlas

3. Axis

4. Cervical vertebrae

5. Thoracic vertebrae

6. Lumbar vertebrae

7. Sacral vertebrae

8. Coccygeal/caudal vertebrae

9. True ribs

10. Scapula

11. Humerus

12. Radius

1. Ulna

2. Carpus

3. Metacarpals

4. Carpals

5. Pelvis

6. Femur

7. Tibia

8. Fibula

9. Tarsus

10. Metatarsals

11. Tarsals

12. Phalanges

Avian skeleton

• Can you identify the additional / adapted bones in birds?

• Can you see any key differences in structure?

Avian skeleton

Key differences from mammalian skeleton:

• Compact body, long neck

• Fused bones

• Pneumatic bones

• Medullary bones

• Sternum / keel

• Gained bones

• Uncinate process - extension of ribs, muscle attachment, strengthen ribs

Fused bones  Rigidity

• Furcula (fused collarbone)  support for wings

• Fused thoracic vertebrae  support for wings

• Pelvic girdle (fused ilia, ischia and pubes to synsacrum)  attachment for leg muscles

• Pygostyle (fused tail section)  supports tail feathers

• Carpometacarpus (fused metacarpals and most carpals)  support primary flight feathers

• Tibiotarsus (fused tibia and proximal tarsals)

• Tarsometatarsus (fused metatarsals and distal tarsals)

Task…

What are the following structures, where are they found and what do they do?

Pneumatic bones

Medullary bones

Keel

10 minutes

Pneumatic bones

• Bones with spaces that act as extensions of the birds air sacs and respiratory system

• Skull, humerus, clavicle, keel, pelvic girdle, lumbar vertebrae, sacral vertebrae

• Diving birds (e.g. penguins, cormorants) – less hollow bones to reduce buoyancy and save energy

Medullary bones

• Tibia, femur, pubic bone, ribs, ulna, toe bones, and scapula

• Source of calcium in egg laying birds

• Hen uses 47% of its body calcium to make egg shell – can’t get this from diet alone

• Without these bones, egg shells would be thin and weak

Sternum / Keel

Muscular System - The avian wing

• anchored to keel

• large proportion - 40% of pigeon

• Pectoralis (down)

• Supracoracoideus (up)

Pectoral muscles

What enables flight in birds?

• Hollow bones

• Strutted bones

• Toothless bill

• Feathers

• Large keel

• Rigid thorax

• Pectoral girdle

FLIGHT: The Genius of Birds - Flight muscles

Concept of flight

Lift – counteracts gravity

Propulsion – counteracts drag

Aerofoil shape:

Air faster over top than bottom

Creates lift

Practice exam questions

Name the labelled bone and state its function (2 marks)

Name the labelled bone and state its function (2 marks)

Keel, provides attachment for wing muscles

Name the labelled bone and state its function (2 marks)

Name the labelled bone and state its function (2 marks)

Pygostyle, supports tail feathers

• Define pneumatic bones and explain the function of these in birds (3 marks)

Define pneumatic bones and explain the function of these in birds (3 marks)

- Bones with air spaces in them (1)

- To make the bird more light weight for flight (1) and to provide an extension of the respiratory system (1)

• What is the function of medullary bones in birds (1 mark)

What is the function of medullary bones in birds (1 mark)

- To be a source of calcium for egg laying

• Describe how the bird skeletal system is adapted to flight (5 marks)

Describe how the bird skeletal system is adapted to flight (5 marks)

• Less bones (than mammals/reptiles) to be lightweight (1)

• hollow bones are lightweight(1)

• hollow bones allow more oxygen to be absorbed into blood for exercise/flight(1)

• hollow but contain struts/cross walls/honeycomb to provide strength(1)

• keeled breastbone to anchor wing muscles(1)

• fusion of bones for strength (1)

Accept any other appropriate answer.

Test your knowledge!

• https://academy.allaboutbirds.org/features/birdanatomy/

• (The Cornell Lab of Ornithology)

Task…

Research the different types of feet in birds and give examples of species:

• Anisodactyl

• Zygodactyl

• Tridactyl

• Didactyl

e.g. Passerines

e.g. woodpeckers, most parrots, owls

e.g. emu, quail

e.g. ostrich